Overview

The Happy Valley Water Treatment Plant, completed in 1991, is Adelaide’s largest Water Treatment Plant (WTP), supplying water to approximately 450,000 people from Port Adelaide in the north, Noarlunga in the south and east to the foothills of Glen Osmond and Blackwood. It also includes Adelaide’s CBD and the water originates primarily from the Murray River supplemented by the Mt Bold catchment areas.

The existing Happy Valley WTP SCADA and PLC Control Systems were installed around the late 1980’s and commissioned in 1993. The control systems consisted of distribution PLC networks which provided the basic control and alarm monitoring of the whole plant.

SAGE Automation was awarded the contract to replace and upgrade the legacy TIGERS SCADA System with a dual redundant iFIX SCADA System and SQL database server and replace the existing Toshiba EX-500 master PLC’s with a dual redundant Allen Bradley Control Logix platform over three sites within the plant. Further upgrades included network controls, a fibre optic ring main and UPS battery backup.

Solution

SAGE Automation was commissioned to design and install a PLC control and SCADA system as part of the upgrade at United Water’s Happy Valley WTP. The plant consisted of three separate areas each of which had a main programmable logic controller (PLC) that monitored and actuated local I/O hardware. In addition, a SCADA system provided supervision and control capability for operators. SAGE was engaged by United Water to upgrade the PLC and SCADA hardware in all three areas and perform associated works.

Result

In each of the plant’s three areas, Toshiba PLC systems were replaced with redundant Allen- Bradley ControlLogix-based systems. For all three areas the existing system functionality was retained and improvements made. In addition, a fibre optic backbone was installed connecting each of the plant areas. The backbone was arranged in a ring topology to provide increased reliability in the communication of information. Each of the process controllers communicate with each other and with the SCADA system via the fibre optic backbone.

For each local process, the field I/O modules communicate with their respective main process controllers via a redundant ControlNet network.

Communication between I/O modules and field I/O devices is done through existing field wiring. Hardwired PID controllers were replaced by PLC driven PID control.

The existing distributed arrangement of plant control for each of the plant’s three areas were retained. The SCADA system used as a gateway for inter-PLC communication was replaced with a direct inter-PLC messaging via Ethernet IP with the new fibre-optic backbone used to carry these signals.

The new PLC and SCADA hardware, network and I/O wiring was installed alongside the existing equipment which allowed a large proportion of the commissioning to be done without any disturbance to the plant operation. The new PLC I/O wiring was run up to the existing terminal rail. Field wiring was disconnected at terminal rail and temporary plug in connectors were installed to allow quick and easy change over to/from the existing and new systems.

Prior to starting, commissioning the plant was broken down into modules to enable a phased changeover. A schedule was created which allowed critical areas to be identified and risk analysis performed.